Do you know what a big difference between Ang's Hulk and TIH was? The same difference between Superman Returns and Man of Steel. Hulk had an equal to smash and get smashed back by. He wasn't just swatting flies having an existential crises, he was a hero, going up against a superior force and winning with an old fashioned beatdown.

Any successful Hulk movie will also have this. Now Leader can be there in the background, but Hulk has to fight another gamma monster whom the audience cares about and respects and thinks is menacing. Gamma Dogs won't do.

So unless you can come up with a better answer (Avengers had Thor and an alien invasion), Red Hulk is your ticket to success. Sorry.